Variable stroke pump



May 16, 1944. 5. c1 10 2,348,958

YARIABLE STROKE PUMP 2 sheds-Sheet 2 Patented May 16, 1944 I VARIABLE STROKE PUMP OrlanddCelio, Soleure, Switzerland, assignor to Scintilia Ltd, Soleurc, Switzerland, a corporation of Switzerland Application March 20, 1942, Serial No. 435,574

In Switzerland July 29, 1941 The present invention relates to a slide valve controlled piston engine of the free stroke type, carrying on its shalt mutually displaced eccentries for communicating reciprocating rectilinear motion to the working piston and slide valve,

respectively, the object of the invention being to provide an improved construction as hereinafter indicated.

According to the invention, a slide valve controlled piston engine of variable piston stroke is characterized in that the eccentric device communicating reciprocating rectilinear motion to both the working piston and slide valve, respectively, includes an inner eccentric fast on the shaft of the engine, an adjustable outer eccentric carried by said inner eccentric and having an operative connection with the working piston of the engine, said outer eccentric being combined with an operating mechanism therefor, and a revoluble control eccentric on said shaft, said control eccentric lacing operatively connected with the operating organ oi the slide valve and coupled for adjustment with the outer eccentric of the working piston for adapting the moments of operating of the slide valve to the varying times of the beginning and end of the piston stroke.

Preferably, adjustment of the outer eccentric said eccentric the external toothing meshing with said pinions.

As will be appreciated, this improved construction is marked by a high measure of simplicity and. it is found in actualuse to be exceedingly efiective. It is also relatively inexpensive to produce and it lends itself to neat and attractive design.

The invention is also concerned with a simplifled operative connection between the adjustable outer eccentric and the working piston, said con- 'nectlon comprising a collar embracing said eccentric and mounted for lateral reciprocating movement in a frame which is vertically displaceable in the machine casing and provided with a central boss at the top wherein is rigidly fitted the outer end of the piston rod. v

The invention will now be further described with reference to the accompanying drawings which illustrate apreferred embodiment oi the invention by way of example.

of the working piston is transmitted to the revoluble control eccentric oi the slide valve through the agency of a movement transmitting device, said device including means operative to turn the control eccentric oi the slide valve in the same direction through half the angle which the adjustable outer eccentric of the piston is turned over on the inner eccentric.

Further according to the invention, arrangement is one in which said means comprise one or more pinions revolving on axles attached to the revoluble control eccentric of the slide valve, said pinions being in gear with a fixed external toothing carried by the shai't of the engine and also with anintemally toothed concentric spur wheel-which is freely revoluble forward and backward on said shaft and coupled for.

a preferredrotation with the adjustable outer eccentric of the working pistomwhereby rotation of said spur wheel causes said pinions to turn on their axles and also to rotate about the relatively stationary toothing on the shaft, thereby entraining the revoluble control eccentric with half the angular speed imparted by-the adjustable outer eccentric to said spur wheeh The revoluble control eccentric or the slide valve is preferably seated on a bush keyed to the shaft and carrying adjacent In these drawings:

Fig. 1 is a longitudinal axial section through a slide valve controlled piston engine and the eccentric mechanism according to the invention.

Fig. 2 is a section along the line A-A of Fig. 1,

showing a part of said eccentric mechanism. Q

Fig. 3 is a section along the line 3-3 of Fig. 1 showing another part of said eccentric mechanlsm.

Fig. 4 illustrates by means drawn on a larger scale the operation of the mechanism shown in Fig. 2.

In the Figures 1 I the shaft of a piston engine, which may be rotated by any suitable prime mover, not represented, and turn in ball bearings 2 and 3 mounted in a twopart casing d. 5 designates the working cylinder oi the piston engine which cylinder is shown formed integral with the casing t and wherein reciprocates with a tight fit the working piston d o! the engine. The upper end of the cylinder 5 is closed by-a removable screw plug i. Parallel to the working cylinder 5 is disposed a valve cylinder 8 formed in the casing 4 and communicating. on

the one side, by a passage 9 with the working cylinder 5 of the engine and, on the other side, by

two pipings I0 and II, intended respectively for admission and exhaust of pressure fluid, with a supply chamber. and a pressure chamber-not represented in the drawings. The valve cylinder 8 wntains a reciprocable control valve which is in the term of a slide valve or piston valve cast "with two operating pistons l2 and i3. Thetail rod intermediate said pistons is shown forming of a vector diagram to 3, the numerali designates eccentricity er, and an adjustable outer an annular groove H which upon reciprocating of the slide valve establishes alternatively communication between the working cylinder 5 of the engine and the two pipings l6 and II respectively.

engine is eflected by eccentrics including an inner eccentric |6 fast on the shaft and having an eccentric I! which is angularly displaceable on said'inner eccentric and has an eccentricity e2. The eccentricities er and e: are preferably of equal length so as to-allow of varying the total eccentricity of said eccentric device between the limits and e1+e2 according 'to the relative angular position of the adjustable outer eccentric on the inner eccentric. The outer eccentric I1 is held against axial displacement, on the one side, by a flange 3 fast on the inner eccentric l6 and, on the other side, .by a distance ring shaft is prevented by a pin 26 seated in the shaft and engaging an internal slot 2| of the said ring. The above eccentricdevice is assembled with the working piston 6 of the engine by means of a two-part collar 22 embracing the outer eccentric l1 and mounted for lateral reciprocating movement in a two-part frame 23 (see Fig. 2). The frame is itself vertically reciprocable in guides 24 forming 'a part of the casing 4, and it presents on its top a centrally disposed boss 25 for reception of the lower disc shaped end 26 of the piston rod. The boss 25 is shown having an outer thread 21 engaging a screw cap 28 which forms a passage for the said piston rod. The latter is surrounded by a rigid spring 29 bearing, on the one side, against the disc shaped end 26 of said piston rod and, on the other side, against the screw cap 28. In this way, a rigid axial connection is ob- 9. Rotation of the ring IS on the tically reciprocable in guides 44 forming a part of the casing of the engine; 45 is the central boss formed on top of said frame'for reception of the lower disc-shaped end 46 of the piston rod; 46

, designates the screw cap on said boss, and 46 the The operation of the working piston 6 of the i tained between the working piston 6 and the eccentric device associated therewith, with the advantage, however, of permitting a slight lateral play of the lower end of the piston rod within the boss 25. V

For operating the Pistons I2 and I3 of the slide valve, there is provided a control eccentric 36 which is revoluble on the shaft I. In the present instance, said control eccentric is rotatably seated on a bush 3| keyed to the shaft and carrying adjacent said eccentric an external toothing 32. The eccentric; 36 is shown having two threaded holes 33 symmetrically disposed as to the shaft I and accommodating each a screw bolt 34. The free end of each of said bolts projects beyond the eccentric, and it is formed to act as axle for a pinion 35 meshing, on the one side, with the external toothing 32 on the bush 3| and, on the other side, with an internally toothed spur wheel 36 concentric with and freely revoluble on the shaft The pinions 35 are mounted with a slight axial play between opposite plane faces of m the eccentric 36 and the concentric spur wheel 36, respectively, and are freely revoluble on their axles so as to turn thereabout upon a relative angular displacement of the internal and'external toothings meshing, therewith. The control eccentric 36 is held against axial displacement by a washer 38 and nut 31 screwed on the shaft I.

The operative connection between thecontrol eccentric 36 and the piston rod of the slide valve l2, I3 is the same as has been described relative to the eccentrics l6, I1 01' the working piston 6 of the engine. 42 designates the collar bearing the eccentric 36 which is freely rotatable therein; 43 I is the frame accommodating said collar for latrigid spring interposed between said cap and the disc-shaped end of the piston rod.

The concentric spur wheel 36 is coupled for rotation with the adjustable outer eccentric II. The latter carries, for this purpose, on the side facing the wheel '36 two pivot pins 56 which are parallel to the shaft and spaced at equal distance from the axis of symmetry of the eccentric IT on either side thereof. Upon each of said pins is rockingly mounted a lever 5| provided at one end with a toothing 52,,which toothings are shown meshing with each other along pitch circle arcs of equal radius having their centers in the pivots 56 of the levers (see Fig. 3). The other ends of the levers 5| carry pins 53upon which are applied links 54 .of equal length, said links being pivoted to diametrically opposite pins 55 on the concentric spur wheel 36. Upon turning the outer eccentric H on the inner eccentric l6, the levers 5| are caused to rock about the pivot pins 56 in opposite directions with respect to the outer ec- The adjustable outer eccentric I1 is also coupled with an operating mechanism for varying its angular position on the inner-eccentric l6. Said mechanism comprises a disc 56 keyed to the shaft and carrying two parallel guide bars51 disposed diametrically opposite each other, a sleeve 56 freely rotatable on said shaft, the outer periphery of said sleeve carrying a quick pitch thread 56 which always cooperates with a corresponding complementary thread in a ring 66. Ring 66 is adapted to slide longitudinally on said guide bars. Between the sleeve 56 and the distance ring I! is interposed on-the shaft a distance sleeve 6|.

The sleeve 58 is connected with the outer eccentric H by means of a coupling disc 62 which is shown surrounding the distance sleeve 6| with a certain radial play. The said disc has on its- 65 extending alonga diameter'which is perpendicular to the diameter connecting the projec tions 63; said guide fast on the outer eccentric I1 and lying in the axis of symmetry thereof. The adjustable outer eccentric I is thus'displaceable in the guide of the disc- 62 perpendicularly to the axls'of the shaft and, simultaneously. rotates in unison with rai reciprocating movement and being itself ver said disc; consequently, it is also coupled for rotation with the threaded sleeve '56, .while being freely movable relative thereto in a plane D mdicular to the axis of theshaft, this movement provided a groove or guide engages two projections 66 assaess being possible in either direction as far as required to allow tor rotation 01 the outer eccentric ii on the inner eccentric I 6.

The slide ring 60 which has a steep pitch, threaded engagement with .the sleeve 58 presents a circumferential groove 81 concentric with the shalt I-and adapted to engage the fork shaped end or a lever 68 which is pivoted to the casing l and connected in any known manner to an operating device not shown in the drawings.

The above described piston engine may be employed either as pump or hydraulic motor; the operation of this engine is as follows:

The shaft-I when rotating entrains simultaneously the inner eccentric it together with the adjustable outer eccentric II,. the'whole operating mechanism 58-80 associated with said outer eccentric, and the bush 3| carrying the external toothing 32. Rotation of the outer eccentric ll is transmitted through the lever and link mechanism 50-55 to the concentric spur wheel at so that the internal toothing on the letter.

revolves synchronously with the external tooth- I ing 32. Consequently, also the pinions 35 which are constantly in gear with either one of said toothings partake of this rotation round the axis oi the shaft I without turning about their own axles or bolts 34 and thereby entrain, by means of said bolts, the control eccentric 80 of the slide valve. The eccentrics of both the working piston and slide valve are thus rotated in unison with the shaft I and the operating mechanism 504% carried by said shaft.

As clearly shown in Figs. 1 to 3, the control eccentric 3b of the slide valve is set 90 with the resultant eccentricity oi the eccentrics I8, ll oi! the engine. Supposing, tor'instance, the line of resultant eccentricity of the two eccentrics I6 and Ill be lying in the plane of the drawings, as is the case in Fig. 1; the lineof eccentricity oi the eccentric 38 then extends in a direction perpendicular to the said plane. This mutual angular displacement of the said eccentrics results in. the slide valve i2, I3 being alternately removed from its mid or starting position when the working piston 6 of the engine reverses its stroke. In this way, during downward stroke of the working piston 6, the slide valve I2, I3 may be caused to move upwards for establishing communicationbetween the cylinder 5 and the piping ton B the slide valve I2, I3 will retake its mid position shown in Fig. 1 in which pipings II and ii are out of communication with-the cylinder 5. During upward stroke or theworking piston i the slide valve will be displaced downwards to establish communication between the cylinder 5 and piping I I, while in the upper end position oi the piston B the slide valve will have returned again to its mid position.

Assume that it is desired to vary at a given speed of the shaft I the quantity or fluid delivcred per stroke of the working pistons. For this purpose the outer eccentric II has to be displaced on the inner eccentric I I! so as to alter the effective stroke of the working piston 8, and such displacement is operated by the lever 8!. By turning said lever while the engine is in action, or at rest, the ring 68 having a steep pitch screw thread is displaced on the guide bars I] so that the sleeve 58 with the complementary thread to is rotated on the shaft and the rotation transmitted by the coupling disc 82 to the outer eccentric I'I which-may be adjusted ciriii. In the lower end position 0! the piscumierentially into any desired position according to the piston throw that is required.

The relative angular displacement of the adiustable outer'eccentric I! on the inner eccentric I0 is apparent from the vector diagram in Fig. 4. In this figure, OA-Em designates the eccentricity of the inner eccentric. I8 and AB=ez the eccentricity oi the outer eccentric I'I according to the position of the eccentrics shown in full lines. The resultant eccentricity of both eccentrics is then represented by the vector 013. When displacing the outer eccentric, I'I over an angle a in clockwise direction into the position shown in dotted lines, the resultant eccentricity in the new position will be represented by the vector 00. Since the'eccentricities e1 and e: aresupposed to be of equal length, the resultant vector 0C leads the original resultant vector OB by the angle Thus, when adjusting the angularposition of the adjustable outer eccentric H on the inner eccentric I6 by means of the lever 68, the resultant eccentricity OB of the whole eccentric device is always turned through halt the angle which the outer eccentric I1 is turned over. This reduced angular displacement of the effective eccentricity of the eccentrics I6, I'l must be transmitted to the same degree upon the control eccentric 30 of the slide valve in 'order to maintain the mutual angular displacement of of said eccentric devices unaltered.

The transmission of half the angle of rotation of the outer eccentric ll upon the control eccentric MI of the slide valve is effected through the agency of the internally toothed concentric spur wheel 36 and the pinions 35. The latter are in gear with the external toothing 32' fast on the shaft l and also with the internal toothing carried by the concentric spur wheel 36 mence to turn about the bolts 8% while simultaneously rolling on said external toothing,

thus making the bolts 34 and also the control eccentric 30 travel round the shaftl with half the circumferential velocity imparted to the spur wheel '36 by the outer eccentric ll.

When employing pinions of relative small diameter so as to reduce to a minimum the difference of length between the-radius n and r:

(see Fig 3), the angular velocity may be substituted for the circumferential velocity in the end points of these radii, causing but a little error in. the transmission ratio of the angular displacements transmitted from the spur wheel 38 upon the control eccentric 30. It will be appreciated, therefore, that the control eccentric 30 of the slide valve is always displaced on the shaft I through half the angle which the ad- .Iustable outer eccentric H has beenturned over on the inner eccentric It. The error in the preelse division of the angular-displacement of said outer eccentric is of minor importance and can be compensated by appropriate constructional features, 1. e., by'providing a certain tooth play between the pinions 35 and the external and internal toothings meshing therewith.

It is to be understood that the invention is not limited to what is illustrated in the drawings. In particular, the coupling employed be-. tween the adjustable outer eccentric l1 and the eccentric spur wheel 36 as well as the operating means provided for adjusting said outer eccentric on the inner eccentric It may be varied without departing from th spirit of the invention.

I claim:

1. A slide valv'e controlled reciprocating piston.

' engine of variable piston stroke comprising incombination acylinder; a piston reciprocable therein; a r'eciproicable slide valve serving to control admission and exhaust of fluid to and from Said y n e a driving shaft; an inner eccentric fast on said shaft; an outer eccentric angularly adjustable relatively to said shaft by rotation on said inner, eccentric; adjustable means connecting said outer eccentric in driv-' ing relation with the shaft in its various angular relations; a driving connection between said outer eccentric and said piston servingto reciprocate the piston upon rotation of the shaft; a valve-actuating eccentric angularly adjustable on said shaft; a driving connection between the valve actuating eccentric and-the valve, for reciprocating the valve upon rotation of the shaft; and connecting means for coordinating the angular adjustments of said outer eccentric and of said valve-actuating eccentric compr a planetary gear train interposed between the shaft, the outer eccentric and the valve actuating eccentric, and 50 arranged thatv the angular displacement of the outer eccentric relatively to the shaft will be twice the angulardisplacement of the valve actuating eccentric relatively to the shaft.

2. A slide valve controlled reciprocating pisn en ine of variable piston stroke comprising i: com ination a cylinder; a piston reciprocable therein; a reciprocable slide valve serving to control admission and exhaust o'f fluid to and from said cylinders; a driving shaft; an inner eccentric fast on said shaft; an outer eccentric angularly adjustable relatively to said shaft by rotation on said inner eccentric; adjustable means connecting said outer eccentric in driving relation with the shaft in itsvarious angular relations; a driving connection between said out;- er eccentric and said piston serving to recipro-i cate the piston upon rotation of the shaft: a valve-actuating eccentric angularly adjustable a spur gear fast on the driving shaft; an internally toothed gear concentric with and encircling outer eccentric to rotate on the shaft in com sonance with the angular adjustment of the outer eccentric; and pinions meshing with said gears and journaled on axes moving with the valve-actuating eccentric.

3. A slide valve controlled reciprocating piston engine of variable piston stroke comprising in combination a cylinder: a piston reciprocable therein; a reciprocable slide valve serving to control admission and exhaust of fluid to and from said cylinder; a driving shaft; an inner eccentric-fast on said shaft; an outer eccentric angularly adjustable relatively to said shaft by rotation on said inner eccentric; adjustable means connecting said outer eccentric in driving relation with the shaft in its various angular I 'valve'actuating eccentric comprising a gear fixed said spur gear, said internally toothed gear being swiveled on the shaft and coupled with theon said shaft; a driving connection between-the Senses at the same rate, a

valve actuating eccentric and the valve, for 're- 9 ciprocating the valve upon rotation of the shaft;

to the driving shaft, a gear swiveled on the driving shaft, a connection between the outer eccentric andthe second named gear constraining the gear to assume the angular adjustments of the outer eccentric relatively to the' shaft, and at least one planet pinion interposed between said gears and meshing with both, said pinion being journaled on an axis carried by said valve actuating eccentric.

4. A slide valve controlled reciprocating piston engine of variable piston stroke comprising in combination a cylinder; a piston reciprocable therein; a reciprocable slide valve serving to-control admission and exhaust of fluid to and from said cylinder; a driving shaft; an inner eccentric fast on said shaft; an outer eccentric an'gularly adjustable relatively to said shaft by rotation on said inner eccentric; adjustable means. connecting said outer eccentricin driving relation with the shaft in its various angular relations; a driving connection between said outer eccentric and said piston serving to reciprocate the piston upon-rotation of the shaft; a valve-actuating eccentric angularly adjustable on said shaft; a driving connection between the valve actuating eccentric and the valve, for reciprocating the valve up'on rotation of the shaft; and connecting means for coordinating the angular adjustments of'said outer eccentric and said valve actuating eccentric comprising a gear swiveled on the drive shaft, a pair of levers journaled on the outer eccentric and geared together to move in reverse planet pinion meshing with both said gears and journaled on an axis carried by said valve actuatpair of links connecting I said levers with said 'swiveled gear; a second gear fixed on said driving shaft; and at least one 

